The invention resides in a capacitive voltage divider for measuring high voltage pulses with millisecond impulse duration.
For measuring high voltage pulses in the nano- and microsecond range, simple capacitive voltage dividers are used. The high voltage part of such a divider consists generally of at least one cylindrical condenser, which is disposed within a pressurized insulating gas or an insulating oil. Depending on the desired divider ratio K, the low voltage part of the high voltage divider may be disposed in the same space as the high voltage part (about K less than 100) or it may be arranged separately therefrom (about Kxe2x89xa7100). With commercially manufactured condensers, the voltage divider is generally designed in one or the other of these ways.
In a design in which the capacitive voltage divider is spacially separated into a high voltage and a low voltage part, the capacities often change during operation by the heating of the dielectric material.
In contrast, with an encapsulation in a common dielectric structure the ratio of the capacities C1/C2 does not change, that is, C1/C2 remains constant. The measuring error occurring with temperature changes may well be several percent. This problem of temperature-dependent capacities can be essentially eliminated by avoiding the spatially separated arrangements.
In a publication of the Academy of the Sciences of the USSR, Testing Arrangements and Techniques, Vol. 3, Moscow, 1985, G. Kuperman et al., disclose under the title xe2x80x9cHigh Power Precision Pulse Modulatorxe2x80x9d a capacitive voltage divider, whose high voltage divider comprises a series arrangement of condensers C1 and C2. The condensers C1 and C2 are all disposed in transformer oil so that the temperature effect is suppressed. The measurement voltage divider comprises two condensers C3 and C4 arranged in series and is connected to the high potential contact of the condenser C2. The potential between the two condensers C3 and C4 is supplied to a measuring instrument with an input resistance R4, for example, an oscilloscope. If the capacity of the low voltage part C2 at the high voltage divider is substantially higher than the capacity of the upper condenser C3 in the measuring voltage divider, that is if C3 less than  less than C2, a divider ratio is obtained as follows:
K≈((C2+C3)xc2x7C4)/(C1xc2x7C3) 
Such a high voltage divider arrangement is simple and reliable and has a high temperature stability. It is suitable for measuring high voltage pulses, which have durations in the microsecond and nanosecond ranges. However, it is not suitable for measuring pulses in the millisecond range since, at the end of a 1.5 msec pulse, the measuring error may reach 15% and even more.
DE 41 40 506 A1 discloses a high voltage sensing head with a large frequency range. The measuring arrangement consists of a capacitive voltage divider comprising a high voltage cascade and a measuring cascade of condensers wherein the measuring cascade senses the voltage at the lowermost condenser of the high voltage cascade. The voltage signal is supplied to the lowermost condenser of the measuring cascade of the measuring instrument. A resistor, which bridges the upper condenser of the measuring cascade has the same resistance as, that is a resistance corresponding to, the wave resistance of a co-axial cable, that is 50 xcexa9, to obtain an optimal termination for the co-axial cable. The resistor dimensioned in this way has a pure termination function for the signal line. The deviations of the measuring signal obtained thereby from the actual measuring signal, which are proportional to the divided high voltage pulse signal, are substantial, particularly in this msec range. The signal is therefore not useable for control and monitoring tasks.
It is the object of the present invention to provide an arrangement by which the time-dependent value of high voltage pulses with pulse durations in the millisecond range can be precisely measured.
In a capacitive voltage divider for measuring high voltage pulses with millisecond pulse duration comprising a high voltage divider including a first cascade of at least two serially arranged condensers of which one (C1) is disposed at the high potential end and another (C2) is disposed at the low potential end of the cascade, and a measuring voltage divider connected to the other condenser (C2) and including a second cascade of at least first and second serially arranged condensers (C3, C4) arranged respectively, at the high and low potential ends of the second cascade with the second condenser being connected with its low voltage side to a signal supply line leading to a measuring device and an ohmic resistor (R1) arranged in parallel with the first condenser and a resistance (R2) connected to the one and first condensers in parallel with the second condenser (C4), the ohmic resistor (R1) is so dimensioned that
1.1 less than C4R2/C3R less than 1.15. 
The capacitive voltage divider design as it is known from the state of the art and which is suitable for the microsecond range is utilized for the arrangement according to the invention because of its simplicity and reliability. It is modified however in a simple manner to make it suitable for larger time windows. The object to measure precisely also high voltage pulses with pulse durations in the millisecond range is achieved by arranging a suitably dimensioned ohmic resistor R1 in parallel with the condenser C3.
The ohmic resistor is selected such that
1.1 less than C4R2/C3R1 less than 1.15. 
With this arrangement, the accuracy of the voltage measurement with a pulse duration in the millisecond range is improved from presently about xc2x17.5%xe2x80x94depending on the component dimensioningxe2x80x94to less than xc2x10.02%, while maintaining the temperature stability of the capacitive high voltage dividers built in accordance with today""s state of the art.
The representative resistance R2 is characterized by various possible circuit arrangements. They depend on the needs of the measuring techniques. They include a circuit arrangement for suppressing undesired oscillations during the rapid voltage increase of the high voltage pulse. It is materialized by arranging an ohmic resistor R3 in connection with a co-axial cable in the input line to the measuring instrument.
Preferably, the high voltage cascade is disposed in a dielectric medium at least up to the condenser with the lowest potential. With an appropriate containment, the dielectric medium of the cascade of the high voltage divider may be pressurized particularly with a compact structure, which provides for high dielectric strength.
The advantage of such a voltage divider is that immediately after applying a rectangular high voltage pulse the voltage at the input of the measuring instrument or the measuring amplifier is determined by the ratio of the capacities in the high voltage divider. The accuracy of the voltage measurement at the end of the rectangular pulse with millisecond duration is improved by the dimensioning of the resistor above the upper condenser in the measuring voltage divider by orders of magnitude.